Questions tagged [experimental-technique]
filling in the unspecified details of elegant-sounding descriptions of experimental methods.
272 questions
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Experimental setup for 1 dimensional constrained frictionless motion
Physics textbooks are full of examples considering one dimensional constrained motion (in the gravitational field) with neglectible friction.
However I have never seen setups with curved paths where ...
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28 views
Photo Multiplier Tube (PMT) and charge sensitive pre-amplifier
I have an H7195 assembly type Photo Multiplier Tube (PMT) used to be tested for single photon measurement. I would like to use the dynode output to check the spectrum by connecting to a charge ...
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0answers
35 views
How Is Are Parton Distribution Functions (PDFs) Determined In Practice And In Theory?
I have put my actual questions in bold normal font, and the rest of this question clarifies what I mean to be asking, especially in terms of the depth and kinds of information I am looking for. ...
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1answer
60 views
Simple heater (radiation) model for PID constants tuning
I've searched around a lot and maybe I just don't know what exactly to search (and even ask here) for, but I'd like to create a simple model/function of a heater dissipating heat to surrounding air, ...
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1answer
34 views
What does it mean to hear the gravitational waves?
In last few years, I watched a lot of YouTube videos claiming that gravitational waves can be and has been heard. They also play a short audio signal. How do experiments such as LIGO replicate the ...
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0answers
17 views
How to change the diameter of a water stream?
So I am conducting experiments investigating the change of sound as a bucket fills up with water. One of the parameters which changes the sound heard is the diameter of the stream of water filling up ...
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2answers
67 views
Does Michelson-Morley experiment really disprove the existence of aether?
In the MM experiment, the speed of one light beam was supposed to slow down as it moved against the flow of aether, but when it bounced off the mirror, it would be moving in the opposite direction--...
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21 views
Generic modes of light
Typically in second quantization one employs creation and destruction operators for modes which are eigenstates of the momentum: $a_{k}, a^{\dagger}_{k}$ where $k$ is the momentum eigenvalue. The "...
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22 views
What are the dynamics of a rope wrapping around a pole of given radius?
Suppose we drop a mass m from an initial angle $\theta_o$ connected to the pole of radius r with a rope of initial length $l_o$. As the system is released, the rope wraps around the pole, decreasing ...
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2answers
28 views
Do you have an idea for two easy experiments to measure the coefficients of static and sliding friction of a rope wrapped around a steel rod?
I'm researching a phenomenon dependent on the Capstan/Euler-Eytelwein-Equation. To model a simulation, I need the friction coefficients. I came up with the idea of hanging one mass $m_1$ on one side ...
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1answer
61 views
What is the scientific method for finding a theoretical explanation for experimental data?
Say you observe some effect that you did not anticipate in one of your experiments. You have checked the experimental setup and you're sure it's not just a systemic error but an actual measurement of ...
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2answers
33 views
spot welding technique
I am trying to make electrical contacts by the spot welding technique. For Hall effect measurements, the contact size should be as small as possible and the sample is very very thin(0.025mm). But ...
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1answer
77 views
Experimental considerations for measuring the gravitational constant/effects, with two large (1000kg) masses orbiting each other? [closed]
So @uhoh, wanting to get some experimental data to verify Limits on non-Newtonian gravity at length scales larger than 1 meter?, proposed an experiment:
Place two large (1000kg) spherical masses in ...
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0answers
54 views
How did Henry Kater measure distances down one part in $10^5$?
Wikipedia says that in 1817, Henry Kater was able to measure distances accurately enough to get at least five significant figures in a measurement of $g,$ suggesting that he could measure a distances ...
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3answers
1k views
How to fix a bad KF flange?
Here is an interesting question for those who are familiar with vacuum science techniques. In the attached picture we have a damaged surface of a KF flange, which comes from the turbo pump outlet and ...
3
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2answers
175 views
Torricelli's law doesn't seem to apply in an experiment. Why could this be? What is going on?
For physics class we've done this experiment where we would measure the speed of the water escaping from a water bottle through a hole in a side of it. We would calculate the speed through kinematics ...
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1answer
72 views
How can one experimentally measure the velocity of water flowing through a pipe?
I am planning to investigate the effect of bend curvature of a pipe on velocity of water. For this, I will need to find the velocity of water through various pipe bends. Would placing an object in the ...
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21 views
Porous nanostructure in TGA and DSC
How does the porosity in porous nanostructures, such as mesoporous silica, influence the observed response in Thermal Gravimetry Analysis (TGA) vs Differential scanning calorimetry (DSC) thermograms?
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1answer
103 views
What is the most efficient way to pour a liquid through a funnel?
Be it in cooking or an experiment, when transferring liquid from one container to another using a funnel should you:
(a) pour it all straight into the funnel, filling it up and waiting for the liquid ...
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1answer
98 views
Strain gauge vs linear variable displacement transducer
For measuring deformation experiments, it seems that strain gauges and linear variable displacement transducers (LVDT) are commonly used. If the material exhibits geometric linearity, then couldn't we ...
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1answer
68 views
Measure temperature of a heater wire
I would like to measure the temperature of a heating wire (tungsten) that's wrapped around my sample.
Does anyone have a better idea than using a infrared thermometer, which has relatively low ...
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2answers
66 views
Why are gradient and graphs used in labs? [closed]
This may seem like a redundant question but I was wondering why gradient calculations are preferred when calculating a value by experiment as opposed to just plugging in raw values me getting an ...
1
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1answer
52 views
The uncertainty of a toy car's measured average speed
Suppose I have a battery-powered toy car, and I am told to design an experiment which would allow me to determine the average speed of that toy car over, say, a meter, and to account for experimental ...
2
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1answer
64 views
Turning off an inductor: Experimental problems
I am trying to measure the current in dependence of time in turning on and off an inductor.
If I choose an inductor with low inductivity (36 mH) it works for turning on (almost) as expected, but for ...
3
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1answer
66 views
How does one actually 'fire an electron'?
As a mathematician, I have practically zero experience and knowledge of experimental methods. Recently, learning about some famous experiments in the history of quantum physics, I heard about an ...
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1answer
86 views
Significant figures in a practical experimental problem [duplicate]
Here is a question that combines uncertainties in measurements and significant figures.
Consider the following results to measure the value of g:
$$g={9.7,9.8,9.7,10.0,10.1,10.3}$$
Then to four ...
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1answer
25 views
Noise reduction approaches in optical spectral measurement
I am using an optical spectrometer to measure some surfaces in the visible, and since the signal is quite noisy I wondering what would be the best way to reduce the noise.
In particular, are there ...
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2answers
326 views
Methods to convert nitrogen nuclei to oxygen nuclei?
Are there any "safe" method that allows converting the nitrogen into oxygen?
There's Ernest Rutherford that uses alpha particles aimed at the nitrogen to create oxygen and hydrogen.
But are there ...
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1answer
270 views
How to find out the wavelength for the blue led diode?
I need your help as I am stuck and I dont know where to start. I have got four blue leds diode that come with dark blue led lights that I really want to get the same led colours for my 3 fans, but I ...
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4answers
84 views
How are high-energy detectors able to to distinguish between $m_{e}$ and $m_{\mu}$?
I had a teacher pose this interesting question yesterday:
Suppose you're running a high-energy scattering experiment at the LHC. For concreteness, let's suppose it's a 2 to 2 scattering event which ...
6
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0answers
163 views
How to cleave a perovskite single-crystal in vacuum?
I am trying to cleave the lead-halide perovskite in vacuum to study its intrinsic electronic properties using photoelectron spectroscopy, since it is difficult to remove surface adsorption without ...
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1answer
67 views
Phase-shifting by Acousto-Optic modulators
I am working on a project where I need to be able to introduce a phase-shift to a light pulse, without any mechanical parts involved. One of the options is to use an acousto-optic modulator:
...
6
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1answer
482 views
What are the “x” marks in a bubble chamber image?
Upon looking at a decent number of bubble chamber images I noticed an x shape . What particles are producing these trails?
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1answer
30 views
Historic method to produce cophasal illumination before lasers?
In a bunch of old papers, written before lasers, the authors often refer to illumination with the same characteristics as a laser: single spatial mode and temporally lockstep.
For example in: On the ...
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0answers
28 views
How to pass a fiber optic through an aluminum laser enclosure?
This is a very technical question which I think is not typical on this site but it is for experimental physics so I'm trying it out because I can't find a better stack exchange
Problem
I'm trying to ...
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1answer
69 views
X-ray: Observation of absorption edge [closed]
So I am working on this experiment on X-ray and kinda stuck on this last and following section.
I have done the measurements and plotted the graph as required in 1. and 2. See below,
However, I ...
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1answer
46 views
X-ray: Aluminium mass absorption co-efficient vs photon energy [closed]
I am doing this experiment on X-rays and I have to do this part of measuring aluminium mass absorption coefficient vs photon's energy. I have done all the work but now stuck in the last step (step 4). ...
2
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0answers
113 views
Exclusion limits on particle dark matter
I'm trying to make sense on how the upper limits of the cross section of particle dark matter (WIMPs) are computed, like in the figure below. This is taken from an article on dark matter searches.
...
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0answers
26 views
What is the $\eta$-reflection method to estimate the background by CMS?
When I used the "Fastjet Package" to reconstruct jet and calculate the jet-shape, I need to estimate the background. I saw from paper:
"The η-reflection method as the CMS experiment did, i.e., ...
5
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1answer
73 views
How do the LIGO team arrive at the number of round trips in the laser arm etalon?
The quoted number of laser beam round trips in the arm cavity for LIGO on the MIT site is 280 times. How did they arrive such a number? Since the laser frequency is stabilized to less than 1 Hz, the ...
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0answers
55 views
Operational definition of quantum states [closed]
I came across a basic textbook problem. I am clear with the math, but I am not clear with how it is connected with experimental facts.Before stating the actual problem.
Let me quote Karl Krauss from ...
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1answer
33 views
What are Chopper Spectrometers and how are they different from Triple-Axis Spectrometers?
I've been reading about inelastic neutron scattering experiments. Recently encountered these two techniques. Can anybody please tell me why/when are these two techniques used?
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1answer
38 views
control of accommodative and vergence demand with mirror stereoscope
I am setting up a mirror stereoscope for use in psychophysical experiments. The stereoscope will be composed of two beamsplitters equidistant from two computer displays, with the participant sitting ...
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1answer
51 views
Determining Threshold Voltage and Plateau from experimental data
I’ve been trying to figure out how to interpret the following data from the Geiger muller tube
There are only seven data points. Where does the plateau begin? Has the data collection begun after the ...
3
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1answer
292 views
Confusion in the Michelson-Morley experiment about beam-splitter vs compensator
From what I know of the original experiment, the beam-splitter was a half-silvered mirror, and one of the paths had a compensator in the form of a glass plate.
My questions are: (1) Since the glass ...
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2answers
276 views
Torsional Pendulum
Hi from one of my lab classes I had to calculate the moment of inertia
of an object by turning it into a torsional pendulum, and measuring
its period with a known constant A, using the following ...
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2answers
84 views
Not seeing a diffraction pattern, what could be the cause?
Basically took a piece of paper, cut out a small slit with some scissors, and held my phone's flashlight right on the slit. What could be causing the lack of diffraction?
Does the fact that the light ...
4
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3answers
206 views
How to detect a wormhole?
Question
A wormhole is a possible solution to Einstein field equations. As far as I understand, the fact that they are a possible solution does not mean they actually exist.
Are we looking for ...
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0answers
96 views
Magnetic field measured in a rotating frame
Consider that we have a magnet and a magnetometer (a fluxgate magnetometer with a single coil), standing still as shown in fig 1.
In fig 1, the magnetic field measured at the axis (z1) of the ...
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0answers
56 views
What do R-squared values and percentage error indicate about the method of an experiment?
In an experiment, I plotted the data on a graph, and the R-squared value was 0.9996. I then calculated the percentage error, which was 1.47%. I know a high R-squared value indicates low random error, ...
